Mosaic Isodicentric Y Chromosome in a Patient with Mixed Gonadal Dysgenesis

Here, we report a male with mixed gonadal dysgenesis and a mosaic karyotype, 45,X[49]/47,X,idic(Y) (q11.2)x2[4]/46,X,idic(Y) (q11.2)[47]. We used fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) to determine the structural rearrangement and genetic content of the Y chromosome. Our findings emphasize the importance of the use of a combination of cytogenetic and molecular genetics techniques during characterization of a patient with a derivative Y chromosome before any general conclusions can be reached concerning the relative effects of the Y chromosome abnormality and mosaicism on sexual differentiation.